Projector



Dec. 12, 1950 J. A. VAN DEN BROEK 2,534,083

PROJECTOR Filed April 18, 1946 4 Sheets-Sheet 1 JA/v A l AN DEN 15RoKDec. 12, 1950 J VAN DEN BROEK 2,534,083

PROJECTOR Filed April 18, 1946 4 Sheets-Sheet 2 Pi Z IN VEN TOR.

2 7- J N A. VAN 0N5R0E MM a %%W A TTOR/VEYS Dec. 12, 1950 J, VAN DENBROEK 2,534,083

PROJECTOR Filed April 18, 1946 4 Sheets-Sheet 3 .JAN A MAN 00v 5R0EK 12,1950 J. A. VAN DEN BROEK 2,534,083

PROJECTOR Filed April 18, 1946 4 Sheets-Sheet 4 a2 a4 2 96 99 /0# o 92 IE2 7/ r ma F1 5 3 woe/whom JAN/l. VAN DEN BRO/SK Patented Dec. 12, 1950PROJECTOR Jan A. Van den Broek, Ann Arbor, Mich., assignor,

by mesne assignments, to Bradfield and Bidwell, Inc., Ann Arbor, Mich.,a corporation of Michigan Application April 18, 1946, Serial No. 663,135

2 Claims. (Cl. 8824) This invention relates to picture projectionapparatus and is more particularly concerned with so-called stillpicture projection apparatus wherein a picture strip may be moved toselectively frame a picture in the optical path and maintain it there adesired length of time, as for reading and lecture purposes.

In its preferred embodiment the invention will be described asincorporated in a projector especially designed for ceiling projection,as for projecting microphotographed book pages on the ceiling of a roomcontaining bedridden persons, but it will be understood that the filmadvancing and holding mechanism is not so limited.

It is a major object of the invention to provide a novel picture stripfeed arrangement for controllably advancing a picture strip across anexposure aperture.

A further object of the invention is to provide a novel picture stripadvancing and holding apparatus wherein the strip may be selectivelymoved in either direction across an exposure aperture and held inexposure position when movement ceases, together with means forautomaticaly releasing the holding means when the strip is to be moved.Preferably in accomplishment Of this object the holding means isreleased slightly in advance of actuation of movement of the film.

It is still a further object of the invention to provide a novelreleasable presser plate assembly for holding the film flat at theexposure aperture in a projector and actuated in timed relation withmovement of the film in either direction across the aperture.

A further object of the invention is to provide novel alternativelyoperable motor and manual arrangements for moving a picture strip ineither direction across an exposure aperture in a projector or the like.

It is a further object of the invention to provide a reversible filmdrive, which may be optionably driven by motor and manual means, coupledin timed relation with a releasable film presser plate assembly at theexposure aperture in a projector.

A further object of the invention is to provide a novel pivotedfrictional presser plate mounting on a shiftable support thereforwhereby the film is held flat during projection.

A further object of the invention is to provide a novel shiftablesupport for releasably mounting a film presser plate.

A further object of the invention is to provide a novel reversible webdrive apparatus for reversibly feeding a picture strip or like webbetween two reels and particularly novel slip clutch mechanism in theroll drive to compensate for changes in drive torque due to changing webroll diameters.

A further object of the invention is to provide novel one-way driveclutch arrangements in a film transport system.

Further objects of the invention will presently appear as thedescription proceeds in connection with the appended claims and theannexed drawings wherein:

Figure 1 is a side elevation of a ceiling projector embodying theinvention;

Figure 2 is a top plan view of the projector of Figure I particularlyillustrating the film feed path;

Figure 3 is a front elevation of the lamp house showing the maskingplates mounted thereon;

Figure 4 is a front elevation of the projector of Figure 1;

Figure 5 is a substantially isometric View of the film feed and presserplate mechanisms according to a preferred embodiment of the inventionand for incorporation in the projector of Figures 1 to 4;

Figure 6 is an exploded view of the one-way compensating drive clutchmechanism for each film roll shaft;

Figure '7 is a section through the one-way friction drive at the supplyand take-up shafts for the film rolls;

Figure 8 is a section through the one-way clutch drive at the rubberfeed rolls;

Figures 9, 10 and 11 are respectively top plan, side and end elevationsof the spring ratchet used in the reversible drives;

Figure 12 is an enlarged side elevation of the swingable presser platesupport;

Figure 13 is a front elevation of the presser plate support of Figure12;

Figure 14 is an enlarged fragmentary sectional view illustrating thespecial conical frictional pivot connection between the presser plateand support of Figures 12 and 13;

Figure 15 is a front elevation of the pivoted presser plate support;

Figure 16 is an end elevation of the support of Figure 15;

Figure 17 is a bottom plan view of the support of Figures 15 and 16; and

Figure 18 is an enlarged sectional view along line I8-|8 in Figure 15illustrating the presser plate holding tabs.

Referring to Figures 1 to 4, the ceiling projector bonlprises a base I|adapted to be levelly supported by legs |2 on a horizontal surface suchas a table, bench or hospital floor. Rearwardly, a removable lamphousing l3, formed with a grilled ventilating air outlet M on top andreleasably secured to base II as by screws |5, encloses a part of theoptical system comprising an upright projection lamp |6 backed by alightconcentrating reflector H which is optically aligned with the lampfilament and the axis of a condenser lens t8. Lamp I6, reflector IT andlens 18 are suitably supported on base H, and uncovered whenever lamphouse I3 is removed.

Forwardly of lamp housing I3, base H is centrally provided with anupstanding hollow obj ective lens mount l9 internally containing a planereflector 2| and an objective lens assembly 22 having a vertical opticalaxis perpendicular to and coplanar with the optical axis of condensert8. Lamp housing 13 and lens mount [9 are both apertured in alignmentwith condenser It to permit the projection light path.

Interposed in the light path between lens l8 and reflector 2| are twopresser plates 23 and 24 having their adjacent faces perfectly fiat andparallel in vertical planes. Plates 23 and 24 are preferably blocks ofglass or like rigid lighttransparent material.

Rear presser plate 23 is fixedly mounted on lamp house 3. Lamp house l3has its front wall apertured in alignment with the optical axis, theaperture being of a size at least equal to the largest picture size tobe positioned between plates 23 and 24. Referring to Figure 3, asuitable presser plate mounting plate 25 is fixedly supported in spacedrelation to the apertured front wall of lamp house l3, as by rivets 25.Plate 25 is formed with an aperture 2'! in alignment with the opticalaxis and the larger aperture in the front wall of lamp house l3, thisaperture being of dimension of the largest picture element that is to beprojected. Vertical masking blades 28 and 29 formed with inclined camand support slots 30 are mounted on rivets 26, being positioned mainlyby friction in the space between plate 25 and the front wall of lamphousing l3. Adjustment of blades 28 and 29 controls the effectivehorizontal projection light aperture size to suit the picture dimensionsso that variations in picture size on the film strip may be suitablycompensated. Tabs 3| integral with plate 25 are bent over to clamp rearpresser plate 23 (not shown in Figure 3) securely in the light path.

Front presser plate 24 is pivotably mounted on the swingable supportillustrated in Figures 1, 12

and 13 as will appear.

The film transport system comprises generally supply and take up spoolholders 32 and 33 fixed to vertical shafts 34 and 35, identicalcylindrical feed rollers 36 and 31 surfaced with rubber or like highfriction material and fixed to vertical shafts 38 and 39, and the filmgate comprising plates 23 and 24. Idler rollers '50 as illustrated inFigure 2 are provided on upstanding vertical axes on base I between eachfeed roller and the film gate for guiding the film to contact a largeportion of the peripheral surface of the feed rollers so as to insure agood positive friction drive of the film by the feed rollers. Sprockets4|--44 of identical size are provided on the vertical shafts of the filmspools and feed rollers all driven by a common endless chain 45. Areversible electric motor 46 having a reversing winding 40 is mountedwithin base H and has its cal rotor 41 connected to drive chain 45through gear 48 on the rotor shaft, idler gears 49, 5| and 52, gear 53,shaft 54, and a sprocket engaged with chain 45.

Gear 53 is axially slidable with respect to shaft 54 and nonrotatablyconnected thereto, as by a pin 56 and slot 5! connection between thegear hub and shaft. Below gear 53, its hub has rigid therewith a bevelgear 53, and a coiled compression spring 59 surrounding shaft 54 reactsbetween the lower end of shaft 54 and gear 58 to normally bias slidablegear 53 into its illustrated upper position where it is in drivingengagement with gear 52, a suitable stop being provided if desired tolimit upward movement of gear 53. Thus, normally, when motor 4 6 isenergized sprockets 4| to 44 are simultaneously rotated at the sameperipheral speed and all in the same direction.

Sprockets 4| to 44 are respectively connected to shafts 34, 35, 3B and39 by similar resilient toothed one-way drive clutch assembliesindicated at '63-66, and clutches 63 and 66 on the film supply andtake-up shafts also include friction couplings 6| and 62 interposedbetween sprockets 4| and 44 and the respective shafts. The function ofclutches 6366 is to provide reversible positive drive for the film aswill appear in the specific description of them given below. Frictioncouplings 6| and 62 are preferably identical, and the toothed driveclutch assemblies 63-66 are also substantially identical in structure asillustrated in Figures 6-8 and as will be described below.

Optionally with drive by motor 46, the film may be reversibly fed bymanual operation. A lever 61, pivoted about a horizontal axis on a lug68 rigid with base II, is formed with a forked end 69 embracing the hubof gear 53. A vertical plunger 1|, having its operating head 12projecting upwardly through a suitable boss in lens mount L9, isslidable within a stationary sleeve 13 and biased upwardly by a coiledcompression spring 14 so as normally to be slightly spaced from anabutment 15 on lever 61. Spring 14 is mainly housed by head 12. AbutmentI5 is preferably a screw locked by a nut 16 in such adjusted position asto cooperate best with plunger 1|. A horizontal shaft 1'! is suitablyjournalled in base I! with a bevel gear 18 fixed upon its inner end anda handle 19 affixed thereto outside base I When the operator desires tomove the film manually instead of by motor 46, he depresses plunger 1|,thereby rocking lever 6! downwardly and disengaging gears 52 and 53, andengaging bevel gears 58 and 18 so that rotation of handle 19 will rotatesprocket 55 to drive chain 45. Upon release of head 12, springs 59 and14 force the parts to the motor drive position illustrated in Figure 5.

With reference to Figures 6 and '7, the drive connections betweensprocket 4| and shaft 34 are there illustrated. Sprocket 4| is formedwith a boss 8| which is freely rotatably supported upon a bearing 82rigid with a :collar 83 which is secured to shaft 34 as by a set screw.Shaft 34 is suitably rotatably supported within the upper part of baseso that the drive assembly is mounted on its depending end. Theelongated hub of sprocket 4| is provided with diametrically opposite,upwardly open slots 84 adapted to receive lugs 85 integrally bent out ofthe plane of an angular spring metal ratchet disc 86 which is therebynon-rotatably secured to sprocket 4|.

Disc 86 is arcuately slotted to provide thereon a pair ofcircumferentially extending spring fingers 81 lying mainly in the planeof the disc but provided at their outer ends with downwardly bentiprojections or teeth 88 which are diametrically opposite but aresimilarly projecting circumferentially as best illustrated in Figures9-11.

A coiled compression spring 89 surrounds shaft 34, and extends within acentral recess 80 in collar 83 reacting between collar 83 and a loosewasher 92 adapted to be seated at the bottom of a cupshaped annulartoothed ratchet member 93 deep enough to enclose the compressed spring.Member 93 is formed on its cylindrical wall with downwardly projectingteeth 94 adapted to coact with one or the other of resiliently mountedteeth 88 depending on the direction of rotation of sprocket 4I. Cup 93is apertured centrally to loosely pass shaft 34 therethrough.

Above cup 93, shaft 34 is loosely surrounded by an annular flat frictionelement 95 adapted to be contacted on opposed flat sides by the fiat topof cup 93 and the flat bottom of a coupling block 96 secured to shaft 34as by set screw 91. Block 96 is diametrically grooved at 98 to provide arecessed seat for a leaf spring element 99 having outwardly bent endsterminating in axially disposed lugs IN. A second annular frictionelement I02 is formed at diametrically opposite points with peripheralnotches I03 adapted to interfit with spring lugs IOI in assembledposition, and is interposed between the flat upper side of block 96 andthe fiat end of a support boss I05 which depends rigidly from the upperpart of base II and carries a shaft bearing I04.

In operation when sprocket M is rotated counterclockwise as indicated bythe arrow in Figure 5, teeth 88 of disc 86 positively engage the teeth94 of cup 93 to rotate cup 93 in the same direction, and since axiallymovable cup 93, friction element 95 and block 96 are urged into tightfrictional contact by the expanding spring 89, cup 93 in turn drivesshaft 34 counterclockwise winding film on the supply spool.

When sprocket 4| is rotated clockwise in Figure 5, resiliently mountedteeth 88 merely slide over teeth 94 and cup 93 is held stationarythrough friction element 95 and spring 89, so that shaft 34 is notpositively driven.

The drive mechanism on shaft 35 between sprocket 44 and shaft 35 ispreferably the same as that illustrated in Figure '1, the difference,however, being that teeth 88 of the ratchet disc 86 used on shaft 35face opposite to those on the ratchet disc on shaft 34, so that whensprocket 44 is rotated clockwise it positively drives shaft 35 whereaswhen it is rotated counterclockwise it does not drive shaft 35.

Figure 8 illustrates the drive mechanism mounted on the lower end offeed roller shaft 38. There collar 83 which rotatably supports thesprocket is afiixed to shaft 38 as by a set screw and spring ratchetdisc 86 is interposed between sprocket 42 and the toothed cup-shapedmember 93 which is like cup 93 except that cup 93' is rigidly secured toshaft 38 as 'by a set screw. Thus the drive connection between sprocket42 and shaft 38 is simply a one-way clutch omitting the frictioncoupling elements of the supply and takeup drives.

The drive connection between sprocket 43 and shaft 39 is structurallyidentical with that for the other feed roller except that teeth 88 areoppositely disposed in the two drives so that when only one feed roller36 or 31 is ositively driven the take-up spool 33 in Figure 5, chain 45is driven counterclockwise in Figure 5 to thereby positively driveshafts 35 and 39, shafts 34 and 38 being relatively idle and non-drivenby reason of their one-way clutch assembly structure. Thus film is fedpast the exposure aperture at a constant speed by feed roller 31, and isaccumulated on the driven take-up spool at 33. As film is withdrawn fromthe idling supply spool at 32 any tendency of the latter to overrun anddischarge loose film into the machine is overcome by the braking actionof friction disc I92 between shaft 34 and boss I05. Furthermore, as theroll of film on take-up spool 33 increases in diameter it tends todemand more film than is supplied by the constant speed feed of roller31. As a result the film tension increases between roller 31 and thetakeup spool but friction coupling 95 here functions to providesufficient slippage in the take-up spool drive to correlate it to thefilm feed speed of roller 31.

When chain 45 is driven clockwise in Figure 5, only shafts 34 and 38 arepositively driven and film is fed from right to left in Figure 5 byroller 36 to be wound upon the driven supply spool, thus exactlyreversing the above described operation in all respects.

Movable pressure plate 24 is mounted on a swingable frame I06 bestillustrated in Figures 5 and 12-18. Provision is made for automaticallyseparating plates 23 and 24 to release and permit movement of the filmwhenever the film drive is actuated either manually or by motor 46. Ihave also arranged to separate plates 23 and 24 a short time prior toeach driven movement of the film so as to synchronize the film releaseand drive means and thereby insure against injury to the film.

Support I06 comprises parallel vertical arms I01 and I08 maintainedtogether in spaced relation by rigid cross bars I09 and II 0 below thetop wall I09 of base I I as illustrated in Figure 13. As alsoillustrated in Figure 13, arms I 01 and I08, which are strips offlexible metal, are divergingly bent at a point just above their fixedinterconnection at bar I I0 and are provided with knurled outer surfacesIII (Figure 6) adapted to be gripped by an operators fingers for apurpose to appear. I

Support frame I06 at its lower end is rotatably supported on ahorizontal cross rod II2 which in turn is rotatably journaled on thespaced legs of a U-shaped bracket II3 suitable rigidly mounted on base II. Rod I I2 is provided with a forwardly extending portion II4 securedat its front end to an upright member I I5 depending rigidly from lever61, so that, when lever 61 is rocked downwardly by depression of plunger1|, rod H2 is concomitantly rocked counterclockwise in Figure 5, Rigidlysecured to rod I I2, as by set screw H6, is a block 1 carrying a pin II8adapted to contact cross bar I09. Support frame I06 is resilientlybiased clockwise (toward closed portion of the plates 23 and 24) by aspring leaf I I9 riveted at one end to stationary bracket I I3 andhearing at its upper end against bar I09 on the opposite side from pinII8 as illustrated in Figure 12. Spring I I9 is bifurcated to permitrelative movement with pin H8.

Thus, when rod I I2 is rocked by depression of plunger 1|, contact ofpin I I8 with bar I09 rocks support frame I06 clockwise about the axisof rod H2 in Figure 5 against the bias of spring H9, and spring II9returns the frame when the plunger is released. This is a manualarrangement for separating the presser plates 23 and 24 at the time themanual drive is established.

Cross bar I I0 is formed with a groove I2I over which is hooked the endof an arm I22 pivoted to an actuating lever I23 which in turn isintermediately pivoted about a vertical axis pivot I24 stationary withrespect to base II and pivotally connected at its further end to thereciprocable armature I25 of a solenoid I26. A normally open controlswitch I21 is mounted in the field circuit of motor 43. A switch buttonI28 of switch I21 is located for abutment by an adjustable stop screwI29 carried by lever I23 for control synchronization as will appear.Frame I06 is biased toward closed position of plates 23 and 24 by atension spring I3I anchored to base II at one end and attached to barIII] at its other end, so that during all periods when solenoid I26 isdeenergized and plunger 1I released, spring I3I holds the film presserplates closed tightly.

Plate 24 is rigidly clamped in a sheet metal frame I32 (Figures -18)having inturned side and bottom flanges I33 bent over the beveled edgesof plate 24. At opposite sides, frame I32 is provided with integralparallel tabs I34 bent forwardly at right angles to the planar surfaceof plate 24 and formed with aligned circular apertures I35. Asillustrated in enlarged fashion in Figure 14, apertures I35 are each ofoutwardly diverging conical form and are adapted to frictionally fitover similarly shaped conical support and pivot pins I36 and I31 on armsI01 and I 08 respectively.

In order to mount frame I32 on support I06, the operator grips knurledportions III between his thumb and forefinger to fiex the upper ends ofarms I01 and IE8 toward each other and decrease the distance betweenpins I36 and I31 until tabs I34 can be slipped past the outer ends ofthe latter to align apertures I35 with the pins. Then the resilient armsI01 and I08 are released permitting them to flex outwardly expandinglyand insert pins I36 and I31 into apertures I35 and thus hold frame I32on a frictional pivot on support I06. The top of frame I32 is open topermit insertion or removal of glass plate 24.

Frame I32 is thus swingably mounted about a horizontal axis parallel tothe film path. The resilient biasing force of arms I01 and I08 and theconical pivot surfaces coact to provide a friction pivot connection suchthat, when the plate 24 is initially swung to clamp a film between itand plate 23, plate 24 assumes a position parallel to plate 23 and isretained there by the friction at the pivots. This arrangement alsoprovides for ready removal and replacement of plate 24 in addition tothe automatic alignment feature.

The usual 110-volt power line is connected through a selector switchassembly I38 to motor 46, solenoid I26, switch I21, lamp I6 and a motorI39 driving a fan for the lamp cooling system.

In switch assembly I38, a first snap switch MI is adapted to immediatelyclose the circuits of lamp I6 and fan motor I39. Normally open pushbutton switches I42 and I43 control operation and direction of the filmfeed at the operators will and these switches are energized when switchMI is closed. When switch I42 is closed, the circuits of solenoid I26and one side of reversing winding 40 are closed, and the circuit ofmotor 46 is closed except for switch I21. Energization of solenoid I26retracts armature I to rock lever I23, which through arm I22 rockssupport I06 and plate 24 to release the film at the aperture. Thespacing of abutment I29 and switch button I28 is such that switch I21 isnot closed until plates 23 and 24 are appreciably separated so thatmotor 46 which starts when switch 21 is closed does not start to drivethe selected film spool and feed roller until after the film has beenreleased at the film gate. Switch I43 effects the same control as switchI42 except that it energized the other side of the reversing winding andcauses movement of the film opposite to that effected by switch I42.

In practice, switch assembly I38 is a unit connected to the projector bya flexible cord so that a patient, for example, in a hospital bed may,with the projector on the floor beside him, control movement anddirection of the film simply by manipulating buttons at I42 and I43after switch I4I has been turned to ON position.

Switch I21 thus provides for automatic sequential opening of the filmgate and actuation of the film drive when motor 45 is the source ofpower. When the film is manually driven, this sequential operation isobtained by the action of pin I I8 contacting bar I09 to rock supportI06 to open the film gate whenever plunger II is depressed and the partsare so constructed that this is accomplished before gears 58 and 18 aremeshed.

My invention provides a novel projector wherein the film strip isreversibly driven at the will of the operator, and wherein either motoror manual means is available for such drive. The film is fed at constantspeed across the exposure aperture by suitable friction feed rollers,and provision is made at the film roll holding spools for compensatingfor changing film roll diameters so as not to unduly tension or looselydeliver the film.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. In a ceiling projector, a mechanism housing, or removable lamp houseon said mechanism housing, an objective lens assembly upstanding fromsaid housing on a vertical axis, a pair of separable fiat transparentplates providing a film gate on the top of said housing in a verticalplane adjacent and in the optical path of said lens assembly, one ofsaid plates being mounted on said lamp house, film spools rotatable onvertical axes on opposite sides of said film gate on the top of saidhousing, means in said housing operable for selectively driving one orthe other of said spools for reversible feed of said film, and means insaid housing synchronized with said film feed means for separating saidplates during film movement.

2. In a projector having an aperture before which a picture to beprojected is positioned, electric motor driven means for feeding a filmpast said aperture, releasable means for holding the film at saidaperture during projection, a control switch in the motor circuit, andmeans for sequentially releasing said holding means and feeding the filmpast said aperture comprising a member movable to release said holdingmeans adapted to close said switch only after predetermined movement ofsaid member.

JAN A. VAN DEN BROEK.

REFERENCES CITED UNITED STATES PATENTS Name Date Iangheck Jan. 2, 1917Number Number 10 Name Date Darby Aug. 24, 1920 Victor Sept. 22, 1931Franzen et al Aug. 30, 1932 Burchett Sept. 27, 19 32 Hopkins July 23,1935 Draeger Apr. 12, 1938 Schubert July 11, 1939 Schubert Oct. 31, 1939Landrock Feb. 11, 1941 Hopkins Apr. 14, 1942 Berglund June 5, 1945Certificate of Correction Patent No. 2,534,083 December 12, 1950 JAN A.VAN DEN BROEK It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction asfollows:

Column 8, line 57 for the words or removable read a removable;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOffice.

Signed and sealed this 20th day of February, A. D. 1951.

THOMAS F. MURPHY,

Assistant Oommissz'oner of Patents.

Certificate of Correction Patent No. 2,534,083 December 12, 1950 JAN A.VAN DEN BROEK It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction asfollows:

Column 8, line 57, for the Words or removable read a removable;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOfiice.

Signed and sealed this 20th day of February, A. D. 1951.

THOMAS F. MURPHY,

Assistant Gommz'ssz'oner of Patents.

